The invention relates to a tube mounting, in particular of a windshield wiper system of motor vehicles.
Tubular mountings for windshield wiper systems of motor vehicles are known. In general, they comprise a retaining device, also known as a sheet-metal mounting, which is built up from a retaining element, embodied as a tube, with a motor mount welded onto it. The motor mount serves to receive and secure the motor required to drive the wiper system. The tube mounting is secured in stationary fashion to the vehicle body and on both of its free ends has bearings, each for receiving one wiper shaft, to which the wiper arm with the wiper blade is secured.
From German Patent Disclosure DE 196 39 559 A1, a tube mounting is known that on at least one of its two free ends has a bearing for receiving a wiper shaft; the bearing is mounted on at least one free end of the tube mounting by injection molding technology, in particular being extruded on.
The end of the mounting tube onto which the bearing is extruded is closed by being compressed. This prevents injection molding material from getting into the tube interior during the injection molding process. It proves to be disadvantageous here that during the injection molding process the mounting tube is exposed to the high injection pressure, and thus is deformed in the mold during the injection molding; the deformation has both elastic and plastic components. The respective deformations always differ from one another, and thus changes in the outside volume of the tube are unpredictable. In this respect, it proves to be disadvantageous that the volume to be extruded is accordingly quite variable, and for constant fill amounts, the different amounts filling the mold impair the dimensional stability of the bearing and its fastening to the mounting tube.
The tube mounting according to the invention has the advantage that the mounting tube is supported from inside by the sealing plug, thus increasing the resistance to compression of the mounting tube during the injection molding process. As a consequence, the clearance of the mounting tube decreases only insignificantly during the injection molding operation, and thus the fill quantity to be injected can be well adapted to the volume to be filled, thus assuring good dimensional stability of the bearing. The invention advantageously provides that the end of the mounting tube onto which the bearing is extruded is closed by the sealing plug. This first prevents injection molding material from getting into the tube interior. The invention also provides that the end of the mounting tube onto which the bearing is to be extruded is embodied in combination with the sealing plug in such a way that shifting, tearing off or twisting of the bearing on or from the mounting tube is impossible. According to a first variant, the invention provides for suitable perforation of a free end of the mounting tube onto which a bearing is to be extruded. The sealing plug inserted into the open end of the mounting tube has recesses in the region of its circumference, and one or more perforation of the mounting tube face these recesses. The at least one hole in the mounting tube and the recess in the sealing plug are disposed in such a way relative to one another and designed in such a way in terms of size that the edges of the holes protrude at least partway past the recesses, thus forming undercuts inside the mounting tube. During the injection molding, injection molding composition flows into these undercuts, creating a secure, positive connection between the mounting tube and the bearing.
In a further advantageous feature of the invention, the sealing plug, also provided with recesses on a certain portion of its surface, is located on the end of the mounting tube onto which the bearing is extruded. The tube is indented in such a way that the surface of the tube at least partly rests on the recesses of the sealing plug. As a result, the connection between the sealing plug and the mounting tube is positive. The bearing extruded around this indented end of the mounting tube, given suitable shaping of the indentations of the tube, is thus lent a twist-proof seat on the end of the mounting tube from which it cannot be torn off.
According to the invention, the sealing plug is designed on its surface resting on the inside of the mounting tube in such a way that it seals off the tube interior from any invading injection molding composition. The sealing plug also braces the tube interior against the injection pressure, so that no impermissible deformations occur.
To make the bracing of the mounting tube against the injection pressure feasible according to the invention, the length of the sealing plug in the mounting tube is at least as great as the length of the extension of the bearing on the mounting tube.
Further advantageous features of the invention can be learned from the dependent claims.
The method for producing the tube mounting according to the invention is characterized in that the at least one free end of the mounting tube is closed by the sealing plug, then placed in a mold, and after the closure of the mold spray-coated by the injection molding composition, thus forming the bearing.
Further advantageous method steps for producing the tube mounting of the invention can be learned from the dependent claims pertaining to the method.